Highest Mountains in Bolivia

Geography and geomorphology

Nevado Sajama is located in the Sajama Province of the Oruro Department in Bolivia, about 18.6 kilometres (11.6 mi) from the border with Chile. Cholcani volcano lies southeast of Sajama, and another neighbouring volcano, Pomerape, resembles Sajama in its appearance. A road runs along the southeastern flank of the volcano, with additional roads completing a circle around Sajama. The village of Sajama lies on its western foot, with the village of Caripe to the northeast of the mountain and Lagunas to the southwest, and there are a number of farms.

In Bolivia, the Andes mountain chain splits into two branches separated by a 3,500–4,000 metres (11,500–13,100 ft) high plateau, the Altiplano.

Geology

Nevado Sajama is part of the Central Volcanic Zone of the Andes, where volcanism is triggered by the subduction of the Nazca Plate beneath the South America Plate. Changes in the subduction regime took place during the Oligocene and directed an increase of volcanic activity in the region. Volcanoes in the region have ages ranging from Pleistocene to Miocene and grew on top of earlier ignimbrites; the whole volcanic activity was controlled by faults.

The mountain is a stratovolcano located atop several lava domes. The stratovolcano consists of lava flows and pyroclastic material that radiate away from the centre of the volcano. Some parasitic vents occur southeast of Sajama and have produced lava domes and lava flows.

Climate

At Cosapa on the foot of Sajama, annual mean temperatures are about 7.3 °C (45.1 °F) while the town of Sajama sees annual temperatures of 4.3 °C (39.7 °F); precipitation there is about 327 millimetres per year (12.9 in/year). The daily temperature range approaches 40 °C (72 °F) there.

Sajama is located between two climate regimes, a westerly one characterized by a dry climate and the Southeast Pacific High and an easterly one with a moister atmosphere. During the southern hemisphere summer, easterly winds carry moist air towards Sajama where solar insolation then triggers showers and thunderstorms; the moisture ultimately originates in the Atlantic Ocean.

Geology

Like most mountains in the Cordillera Real range, Illimani was formed by the subduction of the Nazca plate under the South American plate, as part of the ongoing Andean orogeny. This tectonic process led to the folding and uplift of igneous and other sedimentary rocks, resulting in the mountain's steep ridges and pronounced layering.

The massif comprises four main summits arranged roughly along a north–south axis, with the southernmost peak being the highest. It is composed primarily of granodiorite and metamorphic rocks. The snow line lies at about 4,570 metres (15,000 ft) above sea level, and its upper ridges are snow-capped year-round.

Glacial coverage is found primarily on Illimani's northern and eastern slopes, which descend from elevations below 4,982 metres (16,350 ft).